var prefix1 = "pds.int";
var postfix1 = "btinternet.com";
var whole = prefix1 + '@' + postfix1;
var mmail = "mail";
var mto = "to:";
var list = "enquiries@ravennaconsultants.co.uk";
document.write('<a href="' + mmail + mto + whole + '">' + list + '</a>');